1. Field of the Invention
The present invention relates to a battery pack with a compact configuration for use as a drive source or backup power supply device for various electronic devices, and a backup power supply device with such a battery pack.
2. Description of the Prior Art
Attention has been directed to the importance of backup power supplies for supplying electric power to an electronic device, not from its own power supply, to ensure its continued operation in the event of a failure of the device power supply which supplies power to various electronic devices due to a power system fault or power service interruption. Such a kind of backup power supply comprises rechargeable batteries which are charged by the electric power supplied from the device power supply, and, when the device power supply fails to function, discharges and supplies the stored electric energy to the electronic device. Heretofore, as the rechargeable batteries, lead cells having a large capacity have solely been used. Recently, attempts have been made to use nickel-metal hydrid rechargeable batteries or lithium-ion rechargeable batteries.
Rechargeable batteries have their battery characteristics greatly variable depending on the battery temperature. Further, it cannot be denied that rechargeable batteries themselves generate heat when they are charged and discharged. Consequently, any backup power supply devices employing rechargeable batteries require some thermal measures to be incorporated therein. If such a backup power supply device is mounted in a casing which houses an electronic device, then the heat generated by the electronic device may be applied directly to the backup power supply device depending on the location of the backup power supply device in the casing. It is thus necessary to position the backup power supply device in the casing in a layout designed with thermal considerations.
However, the tendency of recent electronic devices which are smaller-sized and are made up of highly packed components may possibly limit significantly the location of the backup power supply device. One solution is to place a backup power supply device in a drive bay that is provided for installing an external unit (auxiliary unit) in a box-shaped casing which houses an electronic device. In this case, however, using the drive bay to accommodate the backup power supply device leaves certain problems unsolved as to how to make the backup power supply device compact enough to be fitted in the drive bay while at the same time combining itself with thermal precautions. Moreover, in general, a hard disk drive is frequently positioned below the drive bay of the casing. Since the hard disk acts as a large heat source, the backup power supply device needs to have an additional thermal protection scheme.
It is therefore an object of the present invention to provide a battery pack for use as a drive source or backup power supply device for various electronic devices, which is designed to effectively solve problems of heat generated by rechargeable batteries and thermal problems imposed by external sources and also to be compact.
Another object of the present invention to provide a backup power supply device of compact configuration for use in a drive bay of a casing which accommodates an electronic device, for example, therein.
A battery pack according to the present invention has a rechargeable battery group having a plurality of rechargeable batteries connected in series and/or parallel and arranged in horizontal flat arrays as a flat block, an electric circuit for controlling charging of the rechargeable battery group, two heat radiating plates sandwiching opposite surfaces of the rechargeable batteries of the rechargeable battery group, and a battery case supporting the heat radiating plates so as to be exposed, the electronic circuit and the rechargeable battery group being housed in the battery case with the electronic circuit being positioned at an end of the battery case in the direction of the arrays of the rechargeable batteries.
Preferably, the rechargeable batteries comprise cylindrical nickel-metal hydrid rechargeable batteries arranged in two horizontal flat arrays and connected in series. Each of the heat radiating plates has arcuate recesses defined in a surface thereof held against the cylindrical rechargeable batteries and extending along circumferential surfaces of the cylindrical rechargeable batteries. Each of the heat radiating plates has a flat surface exposed out of the battery case. Each of the heat radiating plates has a surface exposed out of the battery case and having a plurality of grooves defined in regions positioned between adjacent ones of the rechargeable batteries arranged in horizontal flat arrays, the grooves extending in the direction of the arrays of the rechargeable batteries, with regions between the grooves serving as heat radiating fins.
The battery pack further includes power supply wires for charging and discharging the rechargeable batteries and signal wires extending from the electronic circuit, the battery case having an end close to the electronic circuit, the power supply wires and the signal wires extending out of the battery case from the end thereof. Further, the electronic circuit desirably has a function to detect a temperature of the rechargeable batteries, and a function to detect a charged energy of the rechargeable batteries, besides its function to control charging of the rechargeable batteries.
According to the present invention, a battery pack of a flat compact shape can be realized and further it has a structure with an excellent heat radiation capability for effectively radiating heat generated by the rechargeable batteries. The battery pack is thus capable of sufficiently performing rechargeable battery functions, and can easily be handled.
A backup power supply device according to the present invention has the battery pack described above, a case for being mounted in a drive bay in a housing which incorporates an electronic device therein, the battery pack being housed in the case. The backup power supply device is arranged to charge the rechargeable batteries of the battery pack with electric energy supplied from a power supply of the electronic device, and supply electric energy from the rechargeable batteries to the electronic device upon a failure of electric energy supplied to the power supply.
In one preferred embodiment of the present invention, the case has a support supporting the battery pack with a gap defined between an inner surface of the case and the heat radiating plates of the battery pack. The support comprises a burr of a predetermined height projecting from a bottom panel of the case into the case, one of the heat radiating plates being fastened to the bottom panel by a screw threaded through the burr into the one of the heat radiating plates.
The backup power supply device further includes a cooling fan disposed in the case at a rear panel thereof for passing air through the case. The case has an air inlet defined in a front bottom panel thereof for introducing air into the case. The cooling fan is energized to discharge air out of the case when the rechargeable batteries are subject to a temperature rise.
According to the backup power supply device with the above-mentioned configuration of the present invention, since air can effectively flows through the case which accommodates the battery pack therein, thermal problems with the battery pack can effectively be solved. The backup power supply device can be handled with ease because it has a compact low profile and is housed in the case that can be mounted in the drive bay in the housing which incorporates the electronic device therein.
The backup power supply device further includes a display unit mounted on a front panel of the case, the display unit comprising a plurality of selectively energizable display elements mounted on a circuit board disposed behind the front panel, and a light guide of a transparent member mounted in the front panel for guiding light emitted from the display elements to a surface of the front panel, the transparent light guide having a light inlet area facing the display elements and a recess or land in the light inlet area for diffusing and introducing the light emitted from the display elements into the transparent light guide.
Preferably, the transparent light guide comprises a panel having an elongate protrusion fitted in a slit extending transversely in the front panel, the panel having a reverse surface confronting the display elements and coated with a light-shielding member except for the light inlet area. The display unit comprises a plurality of display elements for displaying a charged/discharged state of the rechargeable batteries.
According to the backup power supply device having such a display unit, the visual recognition of the display unit is sufficiently enhanced, and an operating state of the backup power supply device can accurately be displayed regardless of the location of the backup power supply device and hence of the location of the housing of the electronic device which incorporates the backup power supply device.